Cisco ASR 9000 Series System Configuration Guide

Multicast Offload Terminology
These are the different terms associated with the Multicast offload solution.
•
Unicast ISID: It is the ISID value set in 802.1ah header for unicast data packet to satellite and for all
data packets from satellite to represent satellite access port. Unicast ISID is used to identify the
Slot/Subslot/Port of a satellite for unicast packets. It is scoped over a satellite.
•
Multicast ISID: It is the ISID value set in 802.1ah header for multicast data packet from host to satellite
to represent offloaded Multicast Route (S, G) per Ring.
•
Designated Multicast Forwarder: Each satellite selects a host as the designated multicast forwarder
and replicates multicast packets for all receivers (satellite access ports) for route (S, G) from the designated
multicast forwarder.
•
Backup Multicast Forwarder: Multicast packets received from Backup Multicast forwarder are not
replicated on the satellite for access ports.
•
Active Unicast Host: The unicast customer data traffic is switched through Active Unicast Host while
traversing through the satellite.
•
Standby Unicast Host: In case of a lost connection to Active Unicast Host due to failures such as cut
cables or connection interface failure, the Standby unicast host shall become the new Active Unicast
Host.
•
Primary Host: Specifies the Host with the lowest chassis MAC in a Dual head topology.
•
Secondary Host: Specifies the Host with a higher chassis MAC than the Primary Host in Dual head
topology.
Overview of Multicast Offload
As in the case of existing Satellite nV System architecture, the IGMP snooping protocol runs on the satellite
hosts with full Cisco IOS XR Software feature parity even with offload. The joins received on the satellite
access ports reach the active host and gets processed by the IGMP snoop module.
•
The IGMP snoop sync feature running over ICCP protocol synchronizes the joined multicast group
membership information to the other host. This keeps the IGMP protocol state for receivers joining over
satellite access ports in sync across both hosts.
•
The hosts independently offload eligible routes to the relevant satellite devices through SDAC. This
includes the list of local ports that have expressed interest in this route.
•
The joins also get propagated to the core by each of the hosts if they have an active link to the core. This
allows better convergence in case of a redundancy switchover on the satellites.
•
When traffic comes in from the source, a special indication in the satellite 802.1ah encapsulation header
signals the satellite devices about the offloaded route to which this packet belongs to. The host then
transmits the packet out of a dynamically elected master OLE for each route (S,G) on a specific bridge
domain per ring. Then, the satellite devices locally replicate the traffic to all the intended local receivers
on that device.
Cisco ASR 9000 Series Aggregation Services Router nV System Configuration Guide, Release 5.3.x
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Configuring Multicast Offload on the Satellite nV System
Multicast Offload Terminology

Cisco ASR 9000 Series Specifications

General

Brand	Cisco
Model	ASR 9000 Series
Category	Network Router
Language	English